Field of the Invention
The present invention relates to a paper feed device and an image forming apparatus, such as a copying machine, that includes such a paper feed device.
Description of the Related Art
In image forming apparatuses such as a copying machine, a printer and a facsimile machine, a paper feed device is provided. In some paper feed devices, sheets are separated and supplied one by one from the uppermost sheet of sheets stacked on the upper surface of a push-up plate or the like in a sheet storage portion. The sheet is fed out by a pick-up roller which makes contact with, from above, the uppermost sheet of the sheets stacked in the sheet storage portion, and a paper feed roller which receives the sheet further feeds it to the downstream side in a transport direction.
Here, when an inflexible and relatively thin sheet or a curled sheet is fed out from the sheet storage portion, the sheet may enter between the pickup roller and the paper feed roller. Thus, a downstream end of the sheet in the transport direction makes contact with an unintended portion of the paper feed roller, with the result that disadvantageously, the downstream portion of the sheet in the transport direction may be bent or a paper jam may occur. Hence, a technology for guiding the downstream end of the sheet in the transport direction fed out by the pickup roller to a predetermined portion of the paper feed roller is proposed, and an example of the conventional technology thereof is disclosed in Japanese Unexamined Patent Application Publication No. 2006-327727.
The paper feed device disclosed in Japanese Unexamined Patent Application Publication No. 2006-327727 includes a transport guide member which guides the transport of the sheet between the pickup roller and the paper feed roller. In this way, the downstream end of the sheet in the transport direction fed out by the pickup roller is guided to the predetermined portion of the paper feed roller, and thus the bending of the sheet or the paper jam is prevented from occurring in the portion of the paper feed roller, with the result that stable transport performance is maintained.
However, since in the paper feed device disclosed in Japanese Unexamined Patent Application Publication No. 2006-327727, the transport guide member is attached to the shaft portion of the paper feed roller, a retaining ring is needed. Hence, disadvantageously, it is inconvenient and troublesome to attach the transport guide member. Furthermore, since the retaining ring is a relatively small component, it is highly likely that the retaining ring is dropped into the image forming apparatus. Thus, the retaining ring may enter a portion where the retaining ring can cause a failure so as to damage the apparatus.
The present invention is made in view of the foregoing respects and has an object to provide a paper feed device and an image forming apparatus which can transport, with a simpler configuration, a sheet between a pickup roller and a paper feed roller in a suitable manner so as to enhance sheet transport performance.